May 8, 2014 1730 UTC Day 2 Convective Outlook

…THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE ARKLATEX…MID MS VALLEY AND LOWER OH VALLEY…

…SUMMARY…
ISOLATED TO SCATTERED SEVERE THUNDERSTORMS WILL BE POSSIBLE FOR FRIDAY AFTERNOON AND EVENING FROM PORTIONS OF THE ARKLATEX AND LOWER MISSISSIPPI VALLEY NORTHEASTWARD TO THE OHIO VALLEY.

…ARKLATEX/MID MS VALLEY/LOWER OH VALLEY…
AN UPPER-LEVEL TROUGH WILL MOVE EWD FROM THE CNTRL PLAINS INTO THE MID TO UPPER MS VALLEY ON FRIDAY. AT THE SFC…A COLD FRONT WILL ADVANCE SEWD ACROSS THE UPPER MS VALLEY…OZARKS AND SRN PLAINS AS WARM ADVECTION OCCURS IN THE OH AND TN VALLEYS. A CORRIDOR OF MODERATE INSTABILITY IS FORECAST TO DEVELOP AHEAD OF THE FRONT BY AFTERNOON FROM NE TX NEWD ACROSS AR INTO SE MO. CONVECTION SHOULD FIRST INITIATE ALONG THE BOUNDARY IN SRN IL EXPANDING SWWD INTO SERN MO WHERE LARGE-SCALE ASCENT ASSOCIATED WITH THE UPPER-LEVEL TROUGH WILL BE FOCUSED. MORE ISOLATED STORMS SHOULD DEVELOP SWWD ACROSS AR BY EARLY EVENING. AS STORM COVERAGE INCREASES ACROSS THE SLIGHT RISK AREA…SEVERAL CLUSTERS APPEAR LIKELY TO BE MAINTAINED INTO THE EVENING.

NAM FORECASTS SOUNDINGS AT 00Z/SAT FROM SRN IL SWWD INTO SERN MO SHOW MLCAPE VALUES OF 1500 TO 2000 J/KG WITH 0-6 KM SHEAR OF 45 TO 50 KT. THIS SHOULD SUPPORT A SEVERE THREAT AS CELLS DEVELOP DURING THE LATE AFTERNOON. SUPERCELLS WILL BE POSSIBLE ESPECIALLY IF CELLS CAN REMAIN DISCRETE ALONG THE BOUNDARY. THE THREAT FOR LARGE HAIL SHOULD BE CONFINED TO AREAS WHERE STORMS HAVE ACCESS TO THE GREATEST INSTABILITY. IN ADDITION…FORECAST SOUNDINGS SHOW WEST SOUTHWESTERLY UNIDIRECTIONAL WIND PROFILES WITH 0-3 KM LAPSE RATES APPROACHING 8.0 C/KM. THIS SUGGESTS THAT THE BETTER ORGANIZED LINE-SEGMENTS SHOULD BE CAPABLE OF PRODUCING DAMAGING WIND GUSTS. IF SUPERCELL STRUCTURES CAN BE OBTAINED…THEN AN ISOLATED TORNADO THREAT MAY ALSO DEVELOP.

FURTHER SOUTHWEST ACROSS AR AND NRN LA…NAM FORECAST SOUNDINGS AT 00Z/SAT SHOW MLCAPE IN THE 2000 TO 3000 J/KG RANGE. THIS COMBINED WITH 40 KT OF 0-6 KM SHEAR SHOULD SUPPORT SEVERE THUNDERSTORM DEVELOPMENT. HOWEVER…LARGE-SCALE ASCENT IS FORECAST TO BE VERY WEAK WHICH SHOULD MINIMIZE CONVECTIVE COVERAGE. CELLS THAT CAN INITIATE AND BECOME ROOTED IN THIS WEAKLY FORCED ENVIRONMENT MAY BECOME SUPERCELLS WITH LARGE HAIL AND AN ISOLATED TORNADO THREAT. WIND DAMAGE WILL ALSO BE POSSIBLE WITH THE MORE EFFICIENT DOWNDRAFTS.

…CNTRL AND SW TX…
AN UPPER-LEVEL TROUGH WILL MOVE INTO THE SRN PLAINS ON FRIDAY AS A COLD FRONT STALLS ACROSS CNTRL TX FRIDAY AFTERNOON. SFC DEWPOINTS TO THE SOUTHEAST OF THE BOUNDARY SHOULD BE IN THE MID TO UPPER 60S F WITH MODERATE INSTABILITY IN PLACE BY AFTERNOON. AS LOW-LEVEL CONVERGENCE INCREASES ALONG THE BOUNDARY…CELLS SHOULD INITIATE IN THE WEAKLY FORCED ENVIRONMENT. FORECAST SOUNDINGS AT DEL RIO TX AT 21Z/FRI SHOW ABOUT 30 KT OF 0-6 KM SHEAR WITH MLCAPE NEAR 1500 J/KG. THIS COMBINED WITH STEEP LOW TO MID-LEVEL LAPSE RATES MAY BE ENOUGH FOR A MARGINAL THREAT FOR WIND DAMAGE AND HAIL.